In recent years, home care and community care in a doctor's office, a clinic, and so on have developed and the number of early diagnoses and urgent clinical inspections has increased. Accordingly, there has been a demand for analyzers that enable non-professionals of clinical inspections to quickly conduct high-precision measurements for clinical inspections with ease. For this reason, analyzers for POCT (Point of Care Testing) have received attention because the analyzers can conduct reliable inspections in a short time without complicated operations. POCT is a generic name of inspections generally conducted in “locations near patients”, for example, in the consulting rooms of practitioners and specialists, wards, and clinics for outpatients.
A dry-type biosensor such as a chromatography specimen using immune response does not require any adjustments of a reagent and enables an analysis of a target analyte in a liquid sample such as blood and urine only with a simple operation such as dropping of the liquid sample to be inspected. Thus many dry-type biosensors have been put into practical use as typical POCT.
Referring to FIG. 5, the following will describe the configuration and inspecting operation of an immunochromatography specimen according to the prior art.
FIG. 5 is a perspective view showing the configuration of the chromatography specimen according to the prior art.
In FIG. 5, reference numeral 1 denotes a specimen for chromatography (hereinafter called a specimen) and reference numeral 2 denotes a support that supports a chromatography material and is made of a plastic and the like. Reference numeral 3 denotes a developing layer that develops a liquid sample and is made of nitrocellulose and the like. Reference numeral 4 denotes a sample adding part for adding or applying the liquid sample. Reference numeral 5 denotes a labeling reagent retaining part for retaining a labeling reagent that is disposed so as to be melted by the development of a sample on the developing layer. Reference numeral 6 denotes a reagent fixing part for fixing a reagent such as specific protein on a region of the developing layer 3. Reference numeral 7 denotes a water absorbing part for absorbing the liquid sample in the end. Reference numeral 8 denotes a transparent liquid-impermeable sheet material that is made up of plastic tape and the like. The liquid-impermeable sheet material 8 tightly covers a part of the specimen 1 except for end regions upstream and downstream of the specimen 1. The labeling reagent retaining part 5, the reagent fixing part 6, and the water absorbing part 7 are each configured as a part of the developing layer 3.
The operations of the specimen 1 configured thus will be described below.
First, a liquid sample added to the sample adding part 4 starts developing the developing layer 3 and reaches the region of the labeling reagent retaining part 5. Next, a labeling reagent retained in the region of the labeling reagent retaining part 5 is melted by the development of the liquid sample and develops downstream of the developing layer 3 along with the liquid sample. The reagent fixing part 6 is provided on the developing layer 3. When the liquid sample contains a target analyte, specific protein fixed in the reagent fixing part 6 causes a combination reaction with a composite of the target analyte and the labeling reagent and a color reaction occurs in the region of the reagent fixing part 6, whereas when the liquid sample does not contain the target analyte, a combination reaction or a color reaction does not occur. Finally, the liquid sample develops to the water absorbing part 7 in the extreme downstream region of the developing layer 3, so that the operation of the specimen 1 is completed.
At this point, at least a measurement region is tightly covered with the liquid-impermeable sheet material 8 made up of transparent plastic tape and the like, thereby preventing water evaporation. The measurement region ranges from the labeling reagent retaining part 5 located upstream of a surface of the developing layer 3 to the reagent fixing part 6 located downstream of the labeling reagent retaining part 5. Further, the liquid-impermeable sheet material 8 makes it possible to evenly develop the liquid sample over the measurement region and keep constant the concentrations of the liquid sample and the labeling reagent that pass through the measurement region for a certain period of time, so that a chromatography inspection can be conducted with accuracy.
In the case where the labeling reagent is gold colloid particles, a color reaction becomes visible in the reagent fixing part 6, so that the result of a qualitative judgment can be obtained by visual observation. When a semiquantitative or quantitative measurement is necessary with precision, the concentration of the target analyte in the liquid sample can be detected by a method of reading reflection absorbance by using a reflectance spectrophotometer. Further, the concentration of the target analyte can be detected by a method of capturing a coloration result of the specimen 1 as an image by an image pickup device such as a camera and performing arithmetic processing.    Patent Document 1: Japanese Patent Laid-Open No. 2002-14097